Inhibitory effect of 17beta-estradiol on growth and the polyamine metabolism of a human gastric carcinoma cell line (HGC-27)

Twelve undescribed derivatives of ganoderic acid isolated from Ganoderma luteomarginatum and their cytotoxicity against three human cancer cell lines

Lanostane triterpenoids are thought to be the main underlying preclinical antitumor secondary metabolites of the genus Ganoderma. To further explore the potential cytotoxic triterpenoids from Ganoderma luteomarginatum, the ethyl acetate soluble fraction of 95% ethanolic extract was systematically studied. Twelve previously undescribed lanostane-type triterpene acids were isolated from the fruiting bodies of G. luteomarginatum, and their structures were elucidated by extensive spectroscopic analyses. Among them, 11 compounds have an unusual β-configuration for OH-15. All isolates were assessed for cytotoxic activities using three human cancer cell lines (A549, HGC-27, and SMMC-7721) and one human normal cell line (LO2). (17Z)-3β,7β,15β-Trihydroxy-11,23-dioxolanost-8,17(20)-dien-26-oate and (20E)-15β-hydroxy-3,7,11,23-tetraoxolanost-20(22)-en-26-oate exhibited significant selective cytotoxicity against HGC-27 cells and A549 cells, respectively, with IC₅₀ values of 6.82 ± 0.77 and 13.67 ± 1.04 μM, while 3β,7β,15β-trihydroxy-11,23-dioxolanost-8-en-26-oate inhibited the proliferation of both A549 and SMMC-7721 cells. In addition, Hoechst fluorescence 33,258 staining and Annexin V-FITC/PI double staining proved that (17Z)-3β,7β,15β-trihydroxy-11,23-dioxolanost-8,17(20)-dien-26-oate could induce apoptosis in HGC-27 cells. Furthermore, a comparison of the results in this study and previous literature demonstrated that ganoderic alcohols have stronger cytotoxicity than the corresponding derivatives of ganoderic acid in the genus Ganoderma.

Genistein potentiates the effect of 17-beta estradiol on human hepatocellular carcinoma cell line

Background:

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors. This cancer may be due to a multistep process with an accumulation of epigenetic alterations in tumor suppressor genes (TSGs), leading to hypermethylation of the genes. Hypermethylation of TSGs is associated with silencing and inactivation of them. It is well-known that DNA hypomethylation is the initial epigenetic abnormality recognized in human tumors. Estrogen receptor alpha (ERα) is one of the TSGs which modulates gene transcription and its hypermethylation is because of overactivity of DNA methyltransferases. Fortunately, epigenetic changes especially hypermethylation can be reversed by pharmacological compounds such as genistein (GE) and 17-beta estradiol (E2) which involve in preventing the development of certain cancers by maintaining a protective DNA methylation. The aim of the present study was to analyze the effects of GE on ERα and DNMT1 genes expression and also apoptotic and antiproliferative effects of GE and E2 on HCC.

Materials and Methods:

Cells were treated with various concentrations of GE and E2 and the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide assay was used. Furthermore, cells were treated with single dose of GE and E2 (25 μM) and flow cytometry assay was performed. The expression level of the genes was determined by quantitative real-time reverse transcription polymerase chain reaction.

Results:

GE increased ERα and decreased DNMT1 genes expression, GE and E2 inhibited cell viability and induced apoptosis significantly.

Conclusion:

GE can epigenetically increase ERα expression by inhibition of DNMT1 expression which in turn increases apoptotic effect of E2. Furthermore, a combination of GE and E2 can induce apoptosis more significantly.

Effects of 17β-estradiol and estrogen receptor antagonists on the proliferation of gastric cancer cell lines

Purpose

The aims of this study were as follow: 1) to de scribe the expression status of estrogen receptor-α and -β mRNAs in five gastric carcinoma cell lines; 2) to evaluate in vitro the effects of 17β-estradiol and estrogen receptor antagonists on the proliferation of the cell lines.

Materials and Methods

Detection of estrogen receptor-α and estrogen receptor-β mRNA in five human gastric cancer cell lines (AGS, KATO III, MKN28, MKN45 and MKN74) was made by the reverse transcription-polymerase chain reaction system. To evaluate the effect of 17β-estradiol and estrogen receptor antagonists on the proliferation of gastric cancer cell line, the cell lines which expressed both es trogen receptors were chosen and treated with 17β-estradiol and estrogen receptor antagonists (methyl-piperidino-pyrazole and pyrazolo [1,5-a] pyrimidine). Cell proliferation was assessed with the methylthiazol tetrazolium test.

Results

Estrogen receptor-α and estrogen receptor-β mRNAs were expressed in three (KATO III, MKN28 and MKN45) and all of the five gastric cancer cell lines, respectively. At higher concentrations, 17β-estradiol inhibited cell growth of MKN28, MKN45 and KATO III cell lines. Neither estrogen receptor-α nor estrogen receptor-β antagonist blocked the anti-proliferative effect of 17β-estradiol.

Conclusions

Our results indicate that estrogen receptor-β mRNAs are preferentially expressed in gastric cancers and also imply that hormone therapy rather than estrogen receptor blockers may be a useful strategy for the treatment of estrogen receptor-β positive gastric cancer. Its therapeutic significance in gastric cancer are, however, limited until more evidence of the roles of estrogen receptors in the gastric cancer are accumulated.

Effect of genistein on cholesterol metabolism-related genes in a colon cancer cell line

The major soy-derived isoflavones such as genistein has been demonstrated to possess anticarcinogenic activity in animal model systems. The present study was designed to investigate the effects of isoflavone genistein exposure at concentrations ranging from 0.01 to 50 muM on the LDL receptor and HMG-CoA reductase gene expression in the estrogen receptor positive DLD-1 human colon cancer cell line. LDL receptor and HMG-CoA reductase gene expressions were evaluated by reverse transcription followed by real-time PCR. Genistein induced an increase of LDL receptor gene expression and later decrease of HMG-CoA reductase mRNA expression in DLD-1 cells. These findings provide direct evidence on the role of genistein in regulating LDL receptor and HMG-CoA reductase gene expression in colon cancer.

Effects of Lactobacillus rhamnosus GG on proliferation and polyamine metabolism in HGC-27 human gastric and DLD-1 colonic cancer cell lines

Previous in vitro and in vivo studies have suggested that lactobacilli can exert antiproliferative effects on the gastrointestinal epithelium. However, their role in affecting the cellular proliferative mechanisms is not completely clear. The aim of this study was to investigate the effects of increasing concentrations of Lactobacillus rhamnosus strain GG (L. GG) homogenate on cell growth and proliferation (by MTT, [3H]-thymidine incorporation and polyamine biosynthesis) in neoplasms originating from different gastrointestinal tracts. Thus, HGC-27 human gastric cancer cells and DLD-1 human colonic adenocarcinoma cells were evaluated. Besides, in order to verify which bacterial fraction was involved in the antiproliferative effects, the cytoplasm and cell wall extracts were tested separately. Gastric HGC-27 and colonic DLD-1 cells showed significant differences in their proliferative behavior, in particular in their polyamine profile and biosynthesis. Notwithstanding, one and the other proved to be sensitive to the growth inhibition by the highest concentrations of bacterial homogenate. Both HGC-27 and DLD-1 cells were resistant to the bacterial cell wall fractions, whereas increasing cytoplasm fraction concentrations induced an evident antiproliferative effect. These data suggest that cytoplasm extracts could be the responsible for L. GG action on proliferation in these two cell lines from gastric and colonic neoplasms.

Effects of Lactobacillus rhamnosus GG on the cell growth and polyamine metabolism in HGC-27 human gastric cancer cells

Previous in vivo studies have suggested that lactobacilli can exert anti-proliferative effects on the gastric epithelium. However, few data are available on their mechanisms of action. The aim of this study was to investigate the effects of increasing concentrations of Lactobacillus rhamnosus strain GG (L. GG) homogenate on cell growth and proliferation [by 3-(4,5 di-methylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, [(3)H]-thymidine incorporation and polyamine biosynthesis] and apoptosis processes (by Bax/Bcl-2 mRNA expression) in HGC-27 human gastric cancer cells. To verify which bacterial fraction was involved in the antiproliferative and proapoptotic effects, the cytoplasm and cell wall extracts were tested separately. HGC-27 cells were sensitive to the apoptotic induction and growth inhibition by increased concentrations of bacterial homogenate. HGC-27 cells were resistant to the bacterial cell wall fractions, whereas increasing cytoplasm fraction concentrations induced evident antiproliferative and proapoptotic actions. These data suggest that cytoplasm extracts could be responsible for L. GG action on HGC-27 cell proliferation.

Estrogenic induction of cannabinoid CB1 receptor in human colon cancer cell lines

OBJECTIVE

Cannabinoids are a class of compounds that have the ability to activate two specific receptor subtypes, the cannabinoid CB1 and CB2 receptors. CB1 receptor is a G-protein-coupled receptor that is linked to the signal transduction pathways. The cumulative effects of this receptor have important implications in the control of cell survival and cell death having the potential to regulate tumor cell growth. In this connection, interest has been focused on factors such as sex steroid hormones, which regulate CB1 receptor expression. The aim of this study was to investigate the effects of 17beta-estradiol exposure on the CB1 receptor gene and its protein expression in human primary tumor colon cancer cell lines, such as DLD-1, HT-29 and one lymph node metastatic cell line, SW620.

MATERIAL AND METHODS

CB1 gene expression was determined using quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) in DLD-1, HT-29 and SW620 cells treated at different times and doses of 17beta-estradiol exposure. CB 1 protein expression was detected by Western immunoblot.

RESULTS

17beta-estradiol induced CB1 gene expression in all the human colon cancer cells studied. The early induction of CB1 receptor mRNA in DLD-1 and SW620 cells was mediated by the estrogen receptor because the pure estrogen antagonist, ICI 182,780, was able to counteract this effect. Estrogenic induction of the CB1 receptor was also detectable at protein level in all cell types tested.

CONCLUSIONS

The CB1 receptor can be considered an estrogen-responsive gene in DLD-1, HT-29 and SW620 cells. Up-regulation of CB1 expression by 17beta-estradiol is a further mechanism of estrogens to control colon cancer proliferation.

Effects of estradiol and progesterone on gastric mucosal response to early Helicobacter pylori infection in female gerbils

BACKGROUND

Gender differences have been shown regarding the changes in the inflammatory response, gastrin secretion, and gastric acidity during Helicobacter pylori infection.

AIM

To investigate the role of estradiol and progesterone in the changes of the gastric mucosa induced by H. pylori during the early stage of infection in female gerbils.

MATERIALS AND METHODS

Thirty-three adult ovariectomized female gerbils were infected with H. pylori (SS1); 7 days after infection they were treated with low and high doses of estradiol (50 and 250 microg/60 days pellet), progesterone (15 and 50 mg/60 days pellet) and vehicle. Non-ovariectomized infected gerbils were used as control. Gerbils were euthanized after 6 weeks of infection. Histologic evaluation, immunohistochemical detection of proliferation cell nuclear antigen (PCNA), gastrin, and apoptosis by terminal deoxynucleotide nick end labeling (TUNEL) assay were performed. Positive cells for PCNA, TUNEL, and gastrin were counted in 10 oriented glands per animal. Two-sided p = .05 was considered significant.

RESULTS

Estradiol-treated groups showed more intense and extended acute and follicular gastritis compared to the vehicle group, whereas progesterone-treated groups presented less gastritis than the other groups. Proliferation and apoptosis indexes were significantly lower in the vehicle group when compared with those of the control; both indexes were increased in the high-dose estradiol and progesterone groups as compared with those of the vehicle. Grade I nonmetaplastic atrophy was observed in the vehicle and progesterone groups. The high-dose progesterone group showed a significant reduction in the number of gastrin cells.

CONCLUSIONS

Estradiol and progesterone participate in the gastric mucosal response to early H. pylori infection in gerbils.

Effects of genistein on the polyamine metabolism and cell growth in DLD-1 human colon cancer cells

Polyamines and their rate-limiting enzyme, ornithine decarboxylase (ODC), are actively involved in cell growth and differentiation. The phytoestrogen genistein has been demonstrated to possess antitumor properties by influencing proliferation, differentiation, and apoptosis. The aim of this study was to investigate the effects of genistein at concentrations ranging from 0.01 to 100 microM on the polyamine biosynthesis, cell proliferation, and apoptosis in the estrogen receptor-positive DLD-1 human colon cancer cell line. Polyamine levels and ODC activity were evaluated by high performance liquid chromatography and radiometric technique, respectively. The proliferative response was estimated by [3H]-thymidine incorporation and the colorimetric 3-(4,5 di-methylthiazol-2-yl)-2,5-diphenyltetrazolium bromide test. Apoptosis was investigated by DNA fragmentation. Bax and Bcl-2 gene expressions were evaluated by multiplex-polymerase chain reaction. At concentration >or=1 microM, genistein decreased significantly the ODC activity and the polyamine levels. At the same concentration, genistein also increased significantly Bax mRNA expression, but not Bcl-2 mRNA expression. Higher concentrations (>or=10 microM) were needed to obtain a significant inhibition of cell proliferation and DNA fragmentation. The results of this study suggest that genistein can affect growth of DLD-1 cells by both decreasing polyamine biosynthesis and inducing apoptosis. However, further studies are required to assess the true ability of a soy rich diet in modifying colon cancer risk.

Estrogenic regulation of cholesterol biosynthesis and cell growth in DLD-1 human colon cancer cells

OBJECTIVE

The main molecules of cholesterol homeostasis are 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMG-CoAR), the key enzyme of the biosynthetic pathway, and the low-density lipoprotein receptor (LDL-R), which is responsible for the uptake of plasma lipoproteins. The increase in the endogenous cholesterol biosynthesis results in stimulation of DNA synthesis, while the inhibition of cholesterogenesis suppresses cell growth. Estrogens have been reported to regulate hepatic LDL-R expression and modulate cell proliferation in different tissues. In order to clarify the mechanisms of estrogenic growth control in colorectal carcinoma, we have investigated the effects of 17beta-estradiol exposure on LDL-R gene expression and its protein, as well as on HMG-CoAR gene expression, its protein as well as enzyme activity in the DLD-1 human colon cancer cell line. The effect of 17beta-estradiol on both cell growth and apoptosis in this cell line was also investigated.

MATERIAL AND METHODS

LDL-R and HMG-CoAR gene expressions were determined using quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) in DLD-1 cells at different times and doses of 17beta-estradiol exposure. LDL-R and HMG-CoAR protein expression was detected by Western immunoblotting. HMG-CoAR activity was evaluated using a radiometric assay. Cell proliferation was measured by colorimetric MTT test and incorporation of [3H]-thymidine in DNA. Apoptotic death was estimated by DNA fragmentation analysis.

RESULTS

Estrogens induced an early increase of LDL-R, at both mRNA and protein level, and later decreased HMG-CoAR activity and protein expression. DLD-1 cells treated with 17beta-estradiol exhibited inhibition of DNA synthesis and apoptosis.

CONCLUSIONS

The results of this study suggest that estrogens regulate LDL-R and HMG-CoAR and influence cell growth and apoptosis in colon cancer cells.

The influence of Lactobacillus brevis on ornithine decarboxylase activity and polyamine profiles in Helicobacter pylori-infected gastric mucosa

BACKGROUND

Functional probiotics may prevent Helicobacter pylori infection, and some evidence suggests that they also possess antitumor properties. Lactobacillus brevis (CD2) is a functional Lactobacillus strain with peculiar biochemical features, essentially related to the activity of arginine deiminase. This enzyme catalyzes the catabolism of arginine and affects the biosynthesis of polyamines (putrescine, spermidine, and spermine). Polyamines are polycations found in high concentrations in both normal and neoplastic cells. Our aims were: 1, to assess whether oral administration of L. brevis (CD2) affects H. pylori survival in the human gastric mucosa; 2, to evaluate the effects of L. brevis (CD2) on polyamine biosynthesis in gastric biopsies from H. pylori-positive patients.

MATERIALS AND METHODS

For 3 weeks before endoscopy, 22 H. pylori-positive dyspeptic patients randomly received (ratio 1 : 1) high oral doses of L. brevis (CD2) or placebo. Before and after treatment, H. pylori infection was determined by urea breath test (UBT). In gastric biopsies, ornithine decarboxylase activity and polyamine levels were, respectively, evaluated by a radiometric technique and high-pressure liquid chromatography (HPLC).

RESULTS

L. brevis (CD2) treatment did not eradicate H. pylori. However, a reduction in the UBT delta values occurred, suggesting a decrease in intragastric bacterial load. Significantly, L. brevis (CD2) induced a decrease in gastric ornithine decarboxylase activity and polyamine levels.

CONCLUSIONS

Our data support the hypothesis that L. brevis (CD2) treatment decreases H. pylori colonization, thus reducing polyamine biosynthesis. Alternatively, the arginine deiminase activity following L. brevis (CD2) administration might cause arginine deficiency, preventing polyamine generation from gastric cells.

Prognostic significance of tissue-type plasminogen activator (tPA) content in gastric cancer and surrounding mucosa

AIMS

We analyzed the tPA content in primary gastric carcinomas and surrounding mucosa in order to assess the relationship between tPA content, clinicopathological tumor characteristics, and estrogen and progesterone receptor content. We evaluated the prognostic value of this serine protease in gastric cancer patients.

PATIENTS AND METHODS

122 resected gastric neoplasms and 95 adjacent mucosa samples were studied. The tPA content was measured in cytosol by an ELISA method. Cytosolic ER and PgR were measured with a solid phase enzyme immunoassay.

RESULTS

Cytosolic tPA levels in neoplastic tissues (median 1.0 ng/mg prot) were significantly lower (p=0.002) than those found in paired mucosa samples (median 2.3 ng/mg prot). There was no significant association between tPA levels and clinicopathological parameters or PgR content, but tPA levels were significantly correlated with ER content. The intermediate-tPA-content group, corresponding to samples with between 0.3 and 1.70 ng/mg protein, proved to have a significantly high risk of relapse.

CONCLUSIONS

We found a wide variability in tPA levels in gastric carcinoma and adjacent mucosa samples, with significantly decreased levels in tumors and a significantly positive relationship between tPA levels and ER status. There was a non-monotonic relationship between tPA levels and prognosis in patients with gastric cancer.

Molecular cloning and characterization of mouse EBAG9, homolog of a human cancer associated surface antigen: expression and regulation by estrogen

We previously identified a human estrogen-responsive gene, EBAG9 (ER-binding fragment-associated antigen9) (Watanabe, T. et al., Mol. Cell. Biol. 18, 442-449, 1998). It was later reported as RCAS1 (receptor-binding cancer antigen expressed on SiSo cells) that induced apoptosis and suppressed the growth of several cells such as activated T cells (Nakashima, M. et al., Nat. Med. 5, 938-942, 1999). Here, we have isolated both cDNA and genomic DNA of mouse EBAG9/RCAS1. Mouse EBAG9 gene spans about 30 kb in genomic DNA and consists of 7 exons. Mouse EBAG9 cDNA encodes a protein that contains the transmenbrane segment and coiled-coil domain. An alignment between the predicted mouse and human EBAG9 shows a high degree of homology at the amino acid level (98%). Northern and Western blot analyses demonstrate that EBAG9 is expressed in several tissues including the heart, brain, spleen, liver, kidney, and testis, and also in developing embryo. In the uterus, a target organ for estrogen, the EBAG9 was shown to be upregulated in vivo by 17beta-estradiol. To determine the biological action of mouse EBAG9, NIH3T3 fibroblastic cells were incubated with recombinant EBAG9 protein, resulting in suppression of cell growth. These findings suggest that EBAG9 is an in vivo estrogen-responsive gene that inhibits the cell growth.

Oestrogen receptors and microsatellite instability in colorectal carcinoma patients

About 10-15% of sporadic colorectal cancers show microsatellite instability (MIN), a mutator phenotype of mismatch repair genes. It seems that oestrogens may inhibit the pathway to colorectal carcinoma which involves a mismatch repair deficiency. Oestrogen receptorial status was evaluated in the neoplastic tissue and uninvolved surrounding mucosa of 17 MIN-positive and 33 MIN-negative tumours using an immunoenzymatic assay. MIN status was examined using the polymerase chain reaction and specific microsatellite markers. MIN was significantly associated with very low levels of oestrogen receptor in tumour tissue. Our findings suggest that MIN-positive tumours might lose a possible oestrogenic modulation mechanism.